Elongate objects are coated with material for various reasons. For example, hypodermic needles are often coated with lubricious or friction-reducing materials, such as silicone based oils. This provides a low friction outer surface of the needle for purposes of easing the introduction of the needle through the skin of a patient. Various methods and apparatus for applying the coating material to the needle have been used in the past. These include dipping methods in which the needles are dipped lengthwise into a bath containing silicone and solvent. This method presents difficulties and challenges related to handling the silicone and solvents, as well as the lengthy drying times involved, and the ventilation needs due to the use of the solvents.
Other methods that have been employed in the past involve various manners of spraying the coating material onto the needle. Typically, the spraying device will discharge the coating material in a single direction and the material will not flow around the entire exterior of the needle. For this reason, the needle and/or spray dispenser must be rotated to evenly distribute the coating material on the entire exterior surface of the needle. Alternatively, multiple spraying devices may be used to coat all sides of the needle. Either case involves increased complication and expense. The overspray or mist can also present problems in the environment around the equipment or require apparatus for containing the overspray. Due to the viscosity of the fluid coating material, it can also be difficult to achieve the required thin, uniform layer of coating material on the exterior surface of the needle.
It would therefore be desirable to provide a device and method for easily coating an exterior of an elongate workpiece, such as a needle, while addressing various challenges presented by past devices and methods.